CCNA 640-802 Bible - Explain and Select the Appropriate Administrative Tasks Required for A WLAN

1. What is one reason that WPA encryption is preferred over WEP?

A: A WPA key is longer and requires more special characters than the WEP key.

B: The access point and the client are manually configured with different WPA key values.

C: WPA key values remain the same until the client configuration is changed.

D: The values of WPA keys can change dynamically while the system is used.

Correct Answers: D

Explanation:

WPA uses dynamic keys ; WEP uses static keys.

2. Refer to the exhibit. What two facts can be determined from the WLAN diagram? (Choose two.)

A:The area of overlap of the two cells represents a basic service set (BSS).

B:The network diagram represents an extended service set (ESS).

C:Access points in each cell must be configured to use channel 1.

D:The area of overlap must be less than 10% of the area to ensure connectivity.

E:The two APs should be configured to operate on different channels.

Correct Answers: B, E

Explanation:

The Extended Service Set (ESS) uses multiple APs with overlapping microcells to cover all clients. Microcells should overlap by 10–15 percent for data, and 15–20

percent for voice traffic. Each AP should use a different channel.

3. Which spread spectrum technology does the 802.11b standard define for operation?

A: IR

B: DSSS

C: FHSS

D: DSSS and FHSS

E: IR, FHSS, and DSSS

Correct Answers: B

Explanation:

802.11b is a widely adopted standard that operates in the 2.4 GHz range and uses Direct Sequence Spread Spectrum (DSSS).

4. What is the maximum data rate specified for IEEE 802.11b WLANs?

A: 10 Mbps

B: 11 Mbps

C: 54 Mbps

D: 100 Mbps

Correct Answers: B

Explanation:

802.11b supports four data rates: 1, 2, 5.5, and 11 Mbps.

5. Which two statements best describe the wireless security standard that is defined by WPA? (Choose two.)

A:It specifies use of a static encryption key that must be changed frequently to enhance security.

B:It requires use of an open authentication method.

C:It specifies the use of dynamic encryption keys that change each time a client establishes a connection.

D:It requires that all access points and wireless devices use the same encryption key.

E:It includes authentication by PSK.

Correct Answers: C, E

Explanation:

Wi-Fi Protected Access (WPA) is a Wi-Fi Alliance standard.

Uses Temporal Key Integrity Protocol (TKIP) for encryption, dynamic keys, and 802.1x user authentication.

WPA-PSK (Pre shared Key) is a special mode of WPA for home users without an enterprise authentication server and provides the same strong encryption protection.

6. Which additional configuration step is necessary in order to connect to an access point that has SSID broadcasting disabled?

A: Set the SSID value in the client software to public.

B: Configure open authentication on the AP and the client.

C: Set the SSID value on the client to the SSID configured on the AP.

D: Configure MAC address filtering to permit the client to connect to the AP.

Correct Answers: C

Explanation:

Since access point has SSID broadcasting disabled here we need to manually configure client the same SSID value configured on AP so that client can associate with the

AP.

7. You and a co-worker have established wireless communication directly between your wireless laptops. What type of wireless topology has been created?

A: BSS

B: ESS

C: IBSS

D: SSID

Correct Answers: C

Explanation:

Ad-hoc mode or Independent Basic Service Set [IBSS] is simply a group of computers talking wirelessly to each other with no access point (AP).

8. A single 802.11g access point has been configured and installed in the center of a square office. A few wireless users are experiencing slow performance and drops while most users are operating at peak efficiency. What are three likely causes of this problem? (Choose three.)

A:mismatched TKIP encryption

B:null SSID

C:cordless phones

D:mismatched SSID

E:metal file cabinets

F:antenna type or direction

Correct Answers: C, E, F

Explanation:

Cordless phones also work on RF so they conflict with WLAN RF and reduce the performance.

metal file cabinets also act as obstacles for Radio waves in WLAN results in performane loss.

Antenna adds power gain for radio waves if Antenna selected is not correct type or direction is not exact then performance will effect.

9. Which two devices can interfere with the operation of a wireless network because they operate on similar frequencies? (Choose two.)

A:copier

B:microwave oven

C:toaster

D:cordless phone

E:IP phone

F:AM radio

Correct Answers: B, D

10.Which encryption type does WPA2 use?

A: AES-CCMP

B: PPK via IV

C: PSK

D: TKIP/MIC

Correct Answers: A

Explanation:

WPA 2 uses AES-CCMP encryption . AES-CCMP incorporates two sophisticated cryptographic techniques (counter mode and CBC-MAC) and adapts them to Ethernet frames to provide a robust security protocol between the mobile client and the access point.